Depressive and anxiety symptoms frequently overlap. Efficacy of tricyclic antidepressants (TCAs) and classical irreversible monoamine oxidase inhibitors (MAOIs) in anxiety disorders has been demonstrated in results from clinical trials and case reports. The anxiolytic effects of antidepressants are widely believed to be specific and not an epiphenomenon of antidepressant or patholytic effects. In long term treatment, tricyclic antidepressants (TCAs) appear to be effective. However, the poor tolerance of TCAs and the risks associated with conventional irreversible MAOIs are limitations to their usefulness.
Therefore, there is a strong demand for alternative drugs particularly for chronic and long term treatment.
As defined in the DSM III-R (Diagnostic and Statistical Manual of Mental Disorders [Third Edition-Revised], American Psychiatric Association, Washington DC, 1987), anxiety disorders comprise--among others--panic disorder with or without agoraphobia, social phobia, and obsessive compulsive disorder.
Panic disorder is classified as an anxiety disorder because in panic disorder, anxiety is usually the predominant symptom. Panic attacks are defined as discrete episodes of intense fear or apprehension, of sudden onset and not associated with physical exertion. Avoidance behavior is almost always present in panic disorder with agoraphobia.
In the natural course of panic disorder with agoraphobia, spontaneous panic attacks almost always precede the phobic symptoms with most patients developing disabling phobic symptoms within six months after the first onset of spontaneou, unexplained anxiety attack.
The development of severe phobic symptoms coincides with an escalation in the intensity and frequency of the spontaneous panic attacks beyond a tolerable threshold for the patient. When a spontaneous panic attack occurs repeatedly in a specific situation, for example, crowds, a phobic anxiety reaction becomes conditioned to that situation. The disorder generalizes and the disability becomes more severe. The development of phobic symptoms is a function of the frequency and intensity of the spontaneous panic attacks and the situations in which they occur. A phobic disability is conditioned more rapidly in those overwhelming, devastating and frequency spontaneous panic attacks. Once the patient is so conditioned, the phobic anxiety response often persists after the spontaneous panic attacks ends although in the first few years, the phobic disorder is less prominent than the anxiety, hysterical and hypochondriacal symptoms.
Panic disorder is common and disabling. Epidemiological data indicate that the life-time prevalence rate for panic disorder is 1-2%. According to the DSM-III-R, panic disorder is the most common of the anxiety disorders in patients seeking treatment.
Social phobia is classified as an anxiety disorder according to the DSM-III-R since exposure to the specific phobic stimulus almost invariably provokes an immediate anxiety response. Marked anticipatory anxiety occurs if the person is confronted with the necessity of entering into the social phobic situation and such situations are thus usually avoided.
The essential feature of social phobia, according to DSM-III-R, is the persistent fear of one or more situations in which a person is exposed to possible scrutiny by others and fears that he or she may do something or act in a way that will be humiliating or embarrassing. Epidemiological data suggest that approximately 2% of the adult U.S. population meet criteria for social phobia.
In their feared situation, or in anticipation of it, affected individuals can suffer enormous anxiety, as well as sweating, trembling, racing or pounding heart beat, mental confusion, and a desire to flee. Vocational advancement or even work itself may be avoided because of social phobia. Social avoidance and isolation can also become extreme, especially in the more generalized condition. Alcohol abuse is more commonly associated with social phobia than any other anxiety disorder, and frequently represents an attempt at self medication of social fears.
According to DSM III-R, the essential feature of obsessive compulsive disorder is recurrent obsessions, i.e., persistent ideas experienced as intrusive and senseless, or compulsions, i.e., repetitive intentional behavior performed in response to an obsession, that cause distress or interfer with routine activities of the patient.